Updates contribution guidelines for JS object performance
Updates contribution guidelines for JS object performance

In a new section, titled performance, a requirement is added
for JavaScript code to limit the re-creation of objects in
the same scope. An example with jQuery is given with explanation.

Change-Id: I2f0d8392277f65384389d8d20154d645197050af
Partial-Bug: #1412971

luhanhan/horizon,sandvine/horizon,liyitest/rr,coreycb/horizon,Mirantis/mos-horizon,maestro-hybrid-cloud/horizon,yeming233/horizon,promptworks/horizon,mdavid/horizon,pranavtendolkr/horizon,kfox1111/horizon,NCI-Cloud/horizon,mdavid/horizon,bigswitch/horizon,tqtran7/horizon,NCI-Cloud/horizon,Solinea/horizon,Metaswitch/horizon,dan1/horizon-proto,tellesnobrega/horizon,vladryk/horizon,kfox1111/horizon,tqtran7/horizon,blueboxgroup/horizon,yjxtogo/horizon,Daniex/horizon,saydulk/horizon,Hodorable/0602,damien-dg/horizon,redhat-cip/horizon,gerrive/horizon,luhanhan/horizon,endorphinl/horizon,yeming233/horizon,pranavtendolkr/horizon,endorphinl/horizon,doug-fish/horizon,coreycb/horizon,wangxiangyu/horizon,agileblaze/OpenStackTwoFactorAuthentication,takeshineshiro/horizon,Tesora/tesora-horizon,damien-dg/horizon,agileblaze/OpenStackTwoFactorAuthentication,redhat-cip/horizon,henaras/horizon,Dark-Hacker/horizon,django-leonardo/horizon,Solinea/horizon,tsufiev/horizon,eayunstack/horizon,VaneCloud/horizon,idjaw/horizon,vladryk/horizon,CiscoSystems/horizon,liyitest/rr,noironetworks/horizon,Tesora/tesora-horizon,BiznetGIO/horizon,FNST-OpenStack/horizon,endorphinl/horizon-fork,yeming233/horizon,watonyweng/horizon,BiznetGIO/horizon,FNST-OpenStack/horizon,wolverineav/horizon,gerrive/horizon,ChameleonCloud/horizon,pranavtendolkr/horizon,anthonydillon/horizon,BiznetGIO/horizon,doug-fish/horizon,mandeepdhami/horizon,bigswitch/horizon,redhat-openstack/horizon,philoniare/horizon,bac/horizon,idjaw/horizon,mandeepdhami/horizon,Hodorable/0602,FNST-OpenStack/horizon,tsufiev/horizon,RudoCris/horizon,maestro-hybrid-cloud/horizon,kfox1111/horizon,xinwu/horizon,eayunstack/horizon,eayunstack/horizon,openstack/horizon,anthonydillon/horizon,kfox1111/horizon,philoniare/horizon,RudoCris/horizon,takeshineshiro/horizon,sandvine/horizon,gerrive/horizon,noironetworks/horizon,bigswitch/horizon,openstack/horizon,redhat-cip/horizon,dan1/horizon-x509,wolverineav/horizon,dan1/horizon-x509,NeCTAR-RC/horizon,j4/horizon,icloudrnd/automation_tools,VaneCloud/horizon,Dark-Hacker/horizon,henaras/horizon,sandvine/horizon,FNST-OpenStack/horizon,karthik-suresh/horizon,karthik-suresh/horizon,yjxtogo/horizon,j4/horizon,anthonydillon/horizon,wolverineav/horizon,noironetworks/horizon,liyitest/rr,tellesnobrega/horizon,saydulk/horizon,xinwu/horizon,Hodorable/0602,orbitfp7/horizon,blueboxgroup/horizon,luhanhan/horizon,mandeepdhami/horizon,wangxiangyu/horizon,dan1/horizon-proto,philoniare/horizon,Dark-Hacker/horizon,mdavid/horizon,bac/horizon,endorphinl/horizon-fork,newrocknj/horizon,tqtran7/horizon,davidcusatis/horizon,henaras/horizon,Mirantis/mos-horizon,damien-dg/horizon,dan1/horizon-x509,watonyweng/horizon,dan1/horizon-x509,endorphinl/horizon,icloudrnd/automation_tools,xinwu/horizon,orbitfp7/horizon,BiznetGIO/horizon,bac/horizon,philoniare/horizon,orbitfp7/horizon,NCI-Cloud/horizon,bac/horizon,Mirantis/mos-horizon,Solinea/horizon,icloudrnd/automation_tools,coreycb/horizon,dan1/horizon-proto,gerrive/horizon,newrocknj/horizon,anthonydillon/horizon,idjaw/horizon,vladryk/horizon,NeCTAR-RC/horizon,VaneCloud/horizon,Tesora/tesora-horizon,maestro-hybrid-cloud/horizon,RudoCris/horizon,watonyweng/horizon,agileblaze/OpenStackTwoFactorAuthentication,RudoCris/horizon,damien-dg/horizon,VaneCloud/horizon,mdavid/horizon,ChameleonCloud/horizon,dan1/horizon-proto,Tesora/tesora-horizon,Dark-Hacker/horizon,saydulk/horizon,CiscoSystems/horizon,takeshineshiro/horizon,ChameleonCloud/horizon,davidcusatis/horizon,Mirantis/mos-horizon,xinwu/horizon,yeming233/horizon,promptworks/horizon,yjxtogo/horizon,tellesnobrega/horizon,django-leonardo/horizon,CiscoSystems/horizon,takeshineshiro/horizon,saydulk/horizon,django-leonardo/horizon,doug-fish/horizon,tsufiev/horizon,newrocknj/horizon,CiscoSystems/horizon,endorphinl/horizon,izadorozhna/dashboard_integration_tests,endorphinl/horizon-fork,izadorozhna/dashboard_integration_tests,blueboxgroup/horizon,Daniex/horizon,agileblaze/OpenStackTwoFactorAuthentication,openstack/horizon,Daniex/horizon,pranavtendolkr/horizon,karthik-suresh/horizon,bigswitch/horizon,j4/horizon,Metaswitch/horizon,noironetworks/horizon,promptworks/horizon,mandeepdhami/horizon,watonyweng/horizon,sandvine/horizon,Metaswitch/horizon,wangxiangyu/horizon,django-leonardo/horizon,NCI-Cloud/horizon,j4/horizon,coreycb/horizon,promptworks/horizon,henaras/horizon,vladryk/horizon,tellesnobrega/horizon,blueboxgroup/horizon,doug-fish/horizon,luhanhan/horizon,tqtran7/horizon,karthik-suresh/horizon,NeCTAR-RC/horizon,redhat-openstack/horizon,redhat-cip/horizon,redhat-openstack/horizon,redhat-openstack/horizon,liyitest/rr,icloudrnd/automation_tools,Daniex/horizon,davidcusatis/horizon,NeCTAR-RC/horizon,endorphinl/horizon-fork,ChameleonCloud/horizon,davidcusatis/horizon,Metaswitch/horizon,wolverineav/horizon,maestro-hybrid-cloud/horizon,Hodorable/0602,Solinea/horizon,tsufiev/horizon,newrocknj/horizon,orbitfp7/horizon,wangxiangyu/horizon,yjxtogo/horizon,openstack/horizon,idjaw/horizon